#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using P = pair<int, int>;
using PL = pair<lint, lint>;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
#define ALL(a)  (a).begin(),(a).end()
constexpr int MOD = 1000000007;
constexpr lint B1 = 1532834020;
constexpr lint M1 = 2147482409;
constexpr lint B2 = 1388622299;
constexpr lint M2 = 2147478017;
constexpr int INF = 2147483647;
void yes(bool expr) {cout << (expr ? "Yes" : "No") << "\n";}
template<class T>void chmax(T &a, const T &b) { if (a<b) a=b; }
template<class T>void chmin(T &a, const T &b) { if (b<a) a=b; }
int main()
{
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int N, M;
  cin >> N >> M;
  vector<vector<PL>> c(N), d(N);
  REP(i, M) {
    int u, v, cc, dd;
    cin >> u >> v >> cc >> dd;
    u--; v--;
    c[u].push_back(PL(cc, v));
    c[v].push_back(PL(cc, u));
    d[u].push_back(PL(dd, v));
    d[v].push_back(PL(dd, u));
  }
  set<PL> st;
  st.insert(PL(0, 0));
  vector<lint> dist(N, 1e18);
  dist[0] = 0;
  while(!st.empty()) {
    PL pl = *st.begin();
    st.erase(pl);
    REP(i, c[pl.second].size()) {
      if(pl.first + c[pl.second][i].first < dist[c[pl.second][i].second]) {
        dist[c[pl.second][i].second] = pl.first + c[pl.second][i].first;
        st.insert(PL(dist[c[pl.second][i].second], c[pl.second][i].second));
      }
    }
  }
  lint ans = dist[N-1];
  int ptr = N-1;
  while(ptr != 0) {
    REP(i, c[ptr].size()) {
      if(dist[ptr] == dist[c[ptr][i].second] + c[ptr][i].first) {
        c[ptr][i] = PL(d[ptr][i].first, c[ptr][i].second);
        REP(j, c[c[ptr][i].second].size()) {
          if(c[c[ptr][i].second][j].second == ptr) {
            c[c[ptr][i].second][j] = PL(d[ptr][i].first, ptr);
            break;
          }
        }
        ptr = c[ptr][i].second;
        break;
      }
    }
  }
  dist = vector<lint> (N, 1e18);
  dist[0] = ans;
  st.insert(PL(ans, 0));
  while(!st.empty()) {
    PL pl = *st.begin();
    st.erase(pl);
    REP(i, c[pl.second].size()) {
      if(pl.first + c[pl.second][i].first < dist[c[pl.second][i].second]) {
        dist[c[pl.second][i].second] = pl.first + c[pl.second][i].first;
        st.insert(PL(dist[c[pl.second][i].second], c[pl.second][i].second));
      }
    }
  }
  cout << dist[N-1] << endl;
  

}